Dual metal interconnection

ABSTRACT

Embodiments relate to a dual metal interconnection structure of a semiconductor device and a method for manufacturing the same. In embodiments, the dual metal interconnection structure may include a contact plug selectively formed in an interlayer dielectric, which covers a silicon substrate, and contacted with an active area of the silicon substrate, a first aluminum interconnection formed on one contact plug in every two cells and having a width larger than a width of the contact plug, a dielectric wrapping an upper surface and a side plane of the first aluminum interconnection, and a second aluminum interconnection formed on one contact plug in every two cells alternatively with the first aluminum interconnection, insulated from the first aluminum interconnection by the dielectric, and having a width larger than a width of the contact plug. The dual metal interconnection structure may be formed by performing an interconnection process two times, and a width of the interconnection and a gap between interconnections may be increased.

The present application claims priority under 35 U.S.C. 119 and 35 U.S.C. 365 to Korean Patent Application No. 10-2005-0134124 (filed on Dec. 29, 2005), which is hereby incorporated by reference in its entirety.

BACKGROUND

A semiconductor memory element, such as a flash memory, may include excellent sensing characteristics, and may have a low bit line resistance. A lower resistance of an interconnection may improve process coverage in a design by increasing the signal process speed and improving the sensing margin.

As semiconductor techniques develop, a size of cells may be reduced. However, a resistance of the interconnection may limit how small a cell size can be reduced. Accordingly it may be important to improve the resistance of the interconnection.

Copper may be used as an interconnection material in an effort to improve the resistance. Since a copper interconnection may have a low specific resistance as compared to an aluminum interconnection, the copper interconnection may be effective to solve a resistance problem of interconnections.

However, since copper interconnection techniques may be more expensive, a product yield may be degraded if the copper interconnection technique is applied to memory products.

A related art metal interconnection structure is shown in FIG. 1.

Referring to FIG. 1, isolation layer 11, which may define an active area, may be formed on silicon substrate 10. Interlayer dielectric 12 may be formed on a surface (for example, the entire surface) of silicon substrate 10.

Contact plug 13, which may be in contact with the active area of silicon substrate 10, may be formed by selectively etching interlayer dielectric 12. Aluminum interconnection 14 may be formed on contact plug 13.

In the metal interconnection structure, since a margin of space may be small, it may be difficult to control a process. Accordingly a change of contact resistance may occur due to a misalignment between aluminum interconnection 14 and contact plug 13.

Moreover, since the metal interconnection structure may have a large aspect ratio due to a shallow gap between aluminum interconnection 14, a void may be caused by not filling the gap between aluminum interconnection 14 if an interlayer dielectric is deposited in a subsequent process.

This may affect a thickness of the interconnection. Accordingly, if a size of cells is reduced, a problem with the interconnection resistance may occur.

SUMMARY

Embodiments relate to a manufacturing technique of a semiconductor device. Embodiments relate to a dual metal interconnection and a method for manufacturing the same for increasing a gap and a width of the metal interconnection by forming one metal interconnection on every two cells twice.

Embodiments relate to a metal interconnection structure of a semiconductor device and a method for manufacturing the same that may be capable of solving a problem related to interconnection resistance, which may occur when size of cells is reduced, obtaining a sufficient process margin, and improving the gap-fill characteristics of an interlayer dielectric.

Embodiments relate to a dual metal interconnection structure and a method for manufacturing the same.

In embodiments, a dual metal interconnection structure may include a contact plug selectively formed in an interlayer dielectric, which covers a silicon substrate, and contacted with an active area of the silicon substrate, a first aluminum interconnection formed on one contact plug in every two cells and having a width larger than a width of the contact plug, a dielectric wrapping an upper surface and a side plane of the first aluminum interconnection, and a second aluminum interconnection formed on one contact plug in every two cells alternatively with the first aluminum interconnection, insulated with the first aluminum interconnection by the dielectric, and having a width larger than the contact plug.

In embodiments of a dual metal interconnection structure, a thickness of the second aluminum interconnection may be larger than the thickness of the first aluminum interconnection, in which the second aluminum interconnection may be partially overlapped with an upper surface of the first aluminum interconnection.

In embodiments of a dual metal interconnection structure, gaps between the first aluminum interconnections and the second aluminum interconnections may be larger than a gap between the contact plugs.

In embodiments a method for manufacturing a dual metal interconnection structure may include a) selectively etching an interlayer dielectric which covers a silicon substrate and forming a contact plug contacted with an active area of the silicon substrate, b) forming a first aluminum interconnection, which may be positioned on one contact plug in every two cells and having a width larger than the contact plug, and a cap dielectric positioned on an upper surface of the first aluminum interconnection by sequentially depositing and selectively etching the first aluminum interconnection and the first dielectric, c) forming a spacer dielectric on both sides of the first aluminum interconnection and the cap dielectric by depositing the second dielectric and performing an etch-back process, and d) forming a second aluminum interconnection formed on one contact plug in every two cells alternatively with the first aluminum interconnection, insulated with the first aluminum interconnection by the cap dielectric and the spacer dielectric and having a width larger than a width of the contact plug.

In embodiments, the second aluminum interconnection may be selectively etched so that the second aluminum interconnection may be deposited thicker than the first aluminum interconnection and may be partially overlapped with an upper surface of the first aluminum.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an example cross section diagram illustrating a related art metal interconnection structure of a semiconductor device; and

FIGS. 2 a to 2 d are example cross section diagrams illustrating a dual metal interconnection structure of a semiconductor device and a method for manufacturing the same in accordance embodiments.

DETAILED DESCRIPTION OF EMBODIMENTS

FIGS. 2 a to 2 d are example cross section views showing a dual metal interconnection structure of a semiconductor device and a method for manufacturing the same in accordance with embodiments.

Referring to FIG. 2 a, isolation layer 21, which may define an active area, may be formed on silicon substrate 20. Isolation layer 21 may be a shallow trench isolation (STI) silicon dioxide film.

Interlayer dielectric 22 may be deposited on a surface (for example, the entire surface) of silicon substrate 20. Contact hole 22 a may then be formed by selectively etching interlayer dielectric 22, and the active area of silicon substrate 20 may be exposed.

Contact plug 23 may be formed within contact hole 22 a, for example by depositing a barrier metal and a tungsten (W) on a surface (for example, the entire surface) of a resultant structure. Contact plug 23 may be planarized, for example until interlayer dielectric 22 is exposed.

Referring to FIG. 2 b, first aluminum interconnection 24 a and cap dielectric 25 positioned on an upper surface of first aluminum interconnection 24 a may be formed, for example by sequentially depositing a first aluminum layer and a first dielectric and then and performing a photolithography process.

Although not illustrated in drawings, a barrier metal layer, such as a titanium/titanium nitrite layer, may be formed on an upper/lower portion of first aluminum interconnection 24 a.

First aluminum interconnection 24 a may be formed to be connected with one contact plug for every two cells (i.e. connected with every other contact plug).

Width W1 of first aluminum interconnection 24 a may be larger than width W2 of contact plug 23.

A width of cap dielectric 25 may be the same as width W1 of first aluminum interconnection 24 a.

Gap S1 between first aluminum interconnections 24 may be larger than gap S2 between contact plugs 23.

Referring to FIG. 2 c, a spacer dielectric may be formed on both sides of first aluminum interconnection 24 a and cap dielectric 25, for example by depositing the second dielectric and performing an etch-back process.

First aluminum interconnection 24 a may thus be surrounded by cap dielectric 25 and spacer dielectric 26.

Referring to FIG. 2 d, second aluminum interconnection 24 b may be formed by depositing a second aluminum layer on a surface (for example, the entire surface) of the resultant structure.

Second aluminum interconnection 24 b may be electrically insulated from first aluminum interconnection 24 a by cap dielectric 25 and spacer dielectric 26.

Although not illustrated, a barrier metal layer, such as a titanium/titanium nitrite layer, may be formed on an upper/lower portion of second aluminum interconnection 24 b.

Second aluminum interconnection 24 b may be formed, and may be connected with one contact plug 23 in every two cells, and may be alternatively formed with first aluminum interconnection 24 a.

Thickness T2 of second aluminum interconnection 24 b may be larger than thickness T1 of first aluminum interconnection 24 a.

Thickness T1 and T2 of first and second aluminum interconnections 24 a and 24 b may be adjusted to have the same resistance.

Width W3 of second aluminum interconnection 24 b may be larger than width W2 of contact plug 23.

Moreover, gap S3 between second aluminum interconnections 24 a may be larger than a gap between contact plugs 23.

According to embodiments, a metal interconnection structure may be formed on every two cells by performing two interconnection processes.

Cap dielectric 25 and spacer dielectric 26, which may be an electrical dielectric material, may be formed between first aluminum interconnection 24 a and second aluminum interconnection 24 b. Second aluminum interconnection 24 b may be formed thicker than first aluminum interconnection 24 a and may partially overlap an upper surface of first aluminum interconnection 24 a.

First and second aluminum interconnections 24 a and 24 b may have a larger width and gap than contact plug 23.

That is, as compared with a related art metal interconnection which may have nearly the same width and gap as the contact plug, the dual layers structure of embodiments may have an increased width and gap.

Accordingly, in a dual layer structure of embodiments, since a space margin increases between layers, it may be easy to control the process. Since an aspect ratio between layers may be improved, the filling in a deposition process of an interlayer dielectric may improve and an occurrence of a void may be prevented.

Moreover, since a width of an interconnection may be increased, a resistance of the interconnection may be reduced and the interconnection may be flexibly used even if a size of a cell is reduced.

In addition, a wide width of the interconnection may prevent a contact resistance from changing due to a misalignment between the interconnection and the contact by obtaining an enough contact margin. Since the thickness of the interconnection may be reduced due to the wide width of the interconnection, a thickness of a photosensitive film may be reduced in a photo process.

It will be apparent to those skilled in the art that various modifications and variations can be made to embodiments. Thus, it is intended that embodiments cover modifications and variations thereof within the scope of the appended claims. It is also understood that when a layer is referred to as being “on” or “over” another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may also be present. 

1. A device comprising: a plurality of contact plugs formed in an interlayer dielectric covering a silicon substrate, each contact plug configured to be in electrical contact with an active area of the silicon substrate; a first aluminum interconnection formed over a first contact plug and having a width larger than a width of the first contact plug; a dielectric covering an upper surface and a side surface of the first aluminum interconnection; and a second aluminum interconnection formed over a second contact plug adjacent to the first contact plug, and further formed over at least a portion of the first aluminum interconnection, insulated from the first aluminum interconnection by the dielectric, and having a width larger than a width of the second contact plug.
 2. The device of claim 1, further comprising a plurality of first aluminum interconnections formed over a plurality of first alternating contact plugs.
 3. The device of claim 2, wherein one first aluminum interconnection is formed for every two alternating contact plugs.
 4. The device of claim 2, further comprising a plurality of second aluminum interconnections formed over a plurality of second alternating contact plugs, each of the plurality of first alternating contact plugs being between each of the plurality of second alternating contact plugs in an alternating pattern.
 5. The device of claim 4, wherein a gap between first aluminum interconnections is greater than a gap between first and second contact plugs.
 6. The device of claim 5, wherein a gap between the second aluminum interconnections is greater than a gap between the first and second contact plugs.
 7. The device of claim 1, further comprising a third aluminum interconnection formed over a third contact plug adjacent to the second contact plug, having a width larger than a width of the third contact plug, and a second dielectric formed over an upper surface and a side surface of the third aluminum interconnection, wherein a size of the third aluminum interconnection is substantially identical to a size of the first aluminum interconnection, and wherein the second aluminum interconnection is formed over at least a portion of the third aluminum interconnection, insulated from the third aluminum interconnection by the second dielectric.
 8. The device of claim 1, wherein a thickness of the second aluminum interconnection is greater than a thickness of the first aluminum interconnection.
 9. The device of claim 8, wherein the second aluminum interconnection partially overlaps an upper surface of the first aluminum interconnection.
 10. The device of claim 1, wherein a gap between the first aluminum interconnections and the second aluminum interconnections is larger than a gap between the contact plugs.
 11. A method comprising: forming a plurality of contact plugs in an interlayer dielectric and in electrical contact with an active area of a silicon substrate; forming a first aluminum interconnection over a first contact plug having a width larger than the first contact plug; forming a cap dielectric over an upper surface of the first aluminum interconnection; forming a spacer dielectric on both sides of the first aluminum interconnection and the cap dielectric; and forming a second aluminum interconnection over a second contact plug adjacent to the first contact plug and over a portion of the first aluminum interconnection, the second aluminum interconnection being insulated from the first aluminum interconnection by the cap dielectric and the spacer dielectric and having a width larger than a width of the second contact plug.
 12. The method of claim 11, wherein the cap dielectric is formed by sequentially depositing and selectively etching a first dielectric over the first aluminum interconnection, and wherein the spacers are formed by depositing a second dielectric over the first dielectric and the first aluminum interconnection and performing an etchback process.
 13. The device of claim 11, further comprising forming a plurality of first aluminum interconnections over a plurality of alternating first contact plugs.
 14. The device of claim 13, wherein one first aluminum interconnection is formed for every two alternating contact plugs.
 15. The device of claim 13, further comprising forming a plurality of second aluminum interconnections over a plurality of alternating second contact plugs, each of the plurality of alternating first contact plugs being between each of the plurality of alternating second contact plugs in an alternating pattern.
 16. The device of claim 11, further comprising forming a third aluminum interconnection over a third contact plug adjacent to the second contact plug, the third aluminum interconnection having a width larger than a width of the third contact plug, and forming a second dielectric over an upper surface and a side surface of the third aluminum interconnection, wherein a size of the third aluminum interconnection is substantially identical to a size of the first aluminum interconnection, and wherein the second aluminum interconnection is formed over at least a portion of the third aluminum interconnection, insulated from the third aluminum interconnection by the second dielectric.
 17. The method as recited in claim 11, wherein the second aluminum interconnection is formed to be thicker than the first aluminum interconnection.
 18. The method as recited in claim 17, wherein the second aluminum interconnection is selectively etched so that the second aluminum interconnection partially overlaps an upper surface of the first aluminum interconnection. 